View Full Version : Steeda Boost bypass

03-13-2009, 09:58 PM

RF Cobra
03-14-2009, 02:17 PM
Welcome to our forums. :)

From what I've seen the best way to make this type of modification is in your tune by a tuner. That was the computer can still control boost pressure to prevent damage. A mechanical bypass such as this prevents the computer from being able to prevent overboost. Comments I've seen on this are it is a waste of money and could be dangerous.

I'd say let your tuner adjust it in the programming and stay away from making mechanical overrides that could cause damage.

From another site:

Many people ask what the bypass valve does. It is integrated in the supercharging system, and when low engine power is required, the bypass valve allows air to enter the engine without passing through the supercharger. Here's how it works:

Under normal engine operating condition vacuum is supplied to the bypass valve. The valve opens, diverting excess airflow back into the air plenum. This prevents

the supercharger from “cavitating.” Cavitating causes reduced performance, increased temperature, and poor fuel economy.

At high engine demands, vacuum is removed from the bypass valve causing it to close. This directs all airflow from the supercharger to the intake manifold.

The supercharger boost (SCB) solenoid is used to control intake manifold vacuum to the vacuum bypass actuator. The PCM transmits an output signal to the SCB solenoid, which activates the solenoid to bypass vacuum when the engine is under maximum boost, reducing the boost pressure by up to 3 PSI.

The purpose of a "Boost Bypass Modification" is to supply continuous boost from your supercharger when the engine is under maximum boost limits. It disables the “abuse” valve in the blower which will bleed boost between shifts if an over boost condition is detected. This mod will NOT provide an increase in performance with the stock pulley.

With the boost bypass modification, you can keep your boost at the maximum level when under WOT (Wide Open Throttle) usage. The term “boost bypass” is a bit misleading. It should really be called a WOT Bypass Mod. This modification does not effect normal engine operation and is designed for modifying boost bypass at WOT only.

There are three common (but not recommended) ways to perform this mod. And one recommended way.


The only way I (and many others) recommend you do the boost bypass is in your tune. Your tuner can assist you. JB on SVTPerformance.com stated the reason very clearly. "Turning it off in the tune in the proper way to do it because it only eliminates the torque management aspects. Mechanically bypassing by disconnecting wiring or re-routing vacuum is NOT the right way because you are eliminating the PCM's ability to pull boost in case of high heat, sensor failures, etc. This is a FAIL-SAFE feature and is something that is foolish to ignore."

Not Recommended

1. Buy a boost bypass kit (Ie. from Steeda). This is a popular method due to claims that it "adds more power". The amount of increased power varies, depending on the amount of boost that is being bled under WOT. Unfortunately vendors who market these bypass kits do not explain the negative side of it.

2. Buy a few parts and install the mod yourself for about $3. <link to directions deleted by me>

3. Disconnect the wire to the boost dump solenoid, but this may cause your check engine light to come on.

site (http://www.stangshiftergaskets.com/2003_2004faqs.htm)

03-14-2009, 08:03 PM

03-25-2009, 01:20 PM
We did this years ago and have had NO problems. :thumbsup:
Free & easy! :bounce:


Good luck with whatever you decide...